New regulator is an air hog?

[671sucba]

Hi everyone! Can anyone tell me if they have had the same problem...I just got a new scubapro regulator and I have become such an air hog! I was never like this with my rental gear. Any advice would be greatly appreciated!

Thanks and happy holidays!

 

[JBRES1]

Hi,
What reg set up did you get ?
You may need to check to see if the cracking pressure is too low on the second stage.
I had a G250v that would blow a little air while I exhaled. I tuned the second stage to a little higher cracking pressure and that took care of my problem.

Jim Breslin

 

[671sucba]

Jim,
Thanks for the quick reply. I have a scuba pro MK25 first stage and scuba pro s600 second stage.

 

[Bubbletrubble]

As Jim mentioned, this may be a simple tuning issue. If the reg is providing more gas than you demand, then it isn't tuned properly. You can simply turn your inhalation adjustment knob "in" to tighten up the reg (increase the cracking pressure). On a related note, in-between dives, remember to store your second stages with the inhalation adjustment knob turned all the way "out" (easiest breathing position). This will minimize wear and tear on the low pressure seat inside.

If manipulating the inhalation adjustment knob doesn't help, then take it to a pro. Your local reg repair tech should be able to do this for little or no charge. If the shop sold you the reg, tuning it should be free of charge. In brief, the tech will verify that the first stage intermediate pressure is in the acceptable range (probably 130 - 150 psi). Then he will remove the second stage from the LP hose and adjust the lever height by turning the crown orifice. No big deal really. The adjustment should only take a few minutes.

Skillful reg tuning strikes a balance between ease of breathing and freeflow. High-end reg setups (like the S600/MK25) are generally tuned more aggressively -- very easy to breathe but may be on the edge of freeflow. Rental regs are usually low- or middle-of-the-line robust, work-horse regs that are tuned to guard against freeflow and breathe a little harder than the high-end regs.

I think my air consumption may have increased slightly after I started using an aggressively tuned reg, but I think having a lower work of breathing was well worth it.

Hope this info helps...

 

[fab50diver]

I've had the same problem with mine. Thanks for the post..will have it checked before my next dive.

 

[Peter_C]

Maybe your dives since certification are deeper, and therefore you are using more air?

 

[herman]

Unless the reg is freeflowing in some manner, there is no way for a reg to cause a higher SAC. An inhaled volume of air is the same reguardless of what type or brand of reg it came from. A freeflow large enough to effect your SAC would be very noticable, there is another problem you are missing, either deeper dives or some other change that you are not taking into account.

 

[Bubbletrubble]

Unless the reg is freeflowing in some manner, there is no way for a reg to cause a higher SAC. An inhaled volume of air is the same reguardless of what type or brand of reg it came from. A freeflow large enough to effect your SAC would be very noticable, there is another problem you are missing, either deeper dives or some other change that you are not taking into account.

@herman: I've experienced the phenomenon of a too-aggressively-tuned reg "forcing" too much gas into my airway upon inhalation. At depth, the reg felt like it was initiating flow too easily and then flowing too long to match my normal breathing pattern (implying a problem with both cracking pressure and Venturi adjustment). The overflow gas simply spilled out of my mouth. I suppose you could call this a freeflow, but it's different from an obvious "hissing" freeflow that occurs topside when the reg is first pressurized.
Given a too-aggressively-tuned reg that I described above, there are a few reasons why the diver might not make the proper adjustment during the dive:

• the second stage lacks adjustment [-]knobs[/-] doohickeys (clearly not the case for the S600),
• the [-]knobs[/-] adjustment doohickeys exist but the diver doesn't know how to make the adjustment, and
• the second stage was tuned with the inhalation adjustment knob turned all the way "in" during tuning (incorrect procedure).

I imagine that such a loss of gas over the entire course of a dive could add up to a significant amount.

On a side note, we forgot to ask the OP how he calculates his SAC rate and what was the difference in his SAC rate between using the rental regs and his new reg. As you and Peter_C pointed out, it may be something besides the reg -- diving in current, diving deeper, leaky LP hose, etc.

 

[herman]

Being force fed by a reg is not caused by aggressive tuning of the cracking pressure, that is the venturi adjustment set too high.

 

[671sucba]

Thanks for all the info. My diving has been the same. No deeper then in the past and the weather conditions here in Micronesia are pretty consistent year round. What I do know is that I went from always having at least 1000 BAR on each dive for a 60 minute dive with my rental gear (which I rented the same set-up for three years) to only being able to make it barely 30 minutes for the same 60 minute dive with my new set-up (no deeper.) I am in good physical condition but can not understand what is causing me to use so much air.

Any help is greatly appreciated. Thanks again!